Spark plug electrode with resistance in center wire



WQQBEG 3 .izector .Qabezzazza Hum-M4130 iv U U 5 6 M y u mw H. RABEZZANA May 29 W34.

SPARK PLUG ELECTRODE WITH RESISTANCE IN CENTER WIRE Filed Jan. 4, 1950 Patented May 29, 1934 UNITED STATES SPARK PLUG ELECTRODE WITH RESISTANCE IN CENTER WIRE Hector Rabezzana, Flint, Mich., assignor to A 0 Spark Plug Company, Flint, Mich, a company of Michigan Application January 4, 1930, Serial No. 418,573 5 Claims. (01. 123-169) This invention relates to spark plugs for internal combustion engines and involves a construction intended to eliminate electrical disturbances that interfere with radio reception.

It is well known that the ordinary ignition system as applied to internal combustion engines is the source of relatively high frequency electrical oscillations that interfere with radio reception. This interference is particularly oblectionable where the automobile or aeroplane is.

equipped with a radio receiving set and in such installations it has been customary to either shield the spark plugs and the high tension leads of the system or to introduce a special resistance in the high tension leads to damp out the interfering waves.

To insert resistance in the circuit for the purpose of reducing radio interference by the damping of the oscillations in a simple and economical manner is one of the primary objects of the present invention. It contemplates the proviison of a spark plug having a resistance element built in as an integral part thereof. Such plug is intended for substitution for the conventional spark plug without any other changes in the engine and its ignition system.

Use of the plug forming the present invention, however, is not limited to engines of radio equipped cars. While primarily designed for such use it can be employed anywhere that spark plugs are ordinarily used. Besides the provision of a plug built to eliminate radio interference the invention has for an object the provision of a. plug that may be manufactured at low cost and assembled easily and quickly and with precision, and, therefore, the invention further aims to provide an improved and simplified method of assembling sparks plugs.

The invention will be better understood upon "reference to the accompanying drawing showing in vertical section a spark plug made according to the invention.

Figure 1 is a central vertical section of a spark plug made in accordance with the invention.

Figure 2 shows a central vertical. section of the upper portion of a modification.

Referring to the drawing the reference character 1 indicates an insulator core made of porcelain, fused quartz, or other suitable di-electric or non-conducting material, which is secured in a shell 2, preferably of steel, and having its inner end screw-threaded for engagement in the customary spark plug opening of the engine. At its lower end the shell 2 carries an electrode or wire 3 which extends beside and in spaced relation later in its shell.

with the lower end of the central electrode carried by the core 1 to afford a spark gap. The central electrode'is shown as consisting of sections 5, 6 and '7. The last-mentioned section '7 carries intermediate its length an abutment collar 9 fixed CI) thereto, with the portions of the section on opposite sides of the collar screw-threaded, one for the attachment of the current conducting lead wire and the other for threaded engagement with an upper screw-threaded portion of the insulator bore. Carbon, porcelain; or other suitable resistance material, makes up the'electrode section 6. An enlarged abutment head 10 on the upper end of the section 5 forms a bearing for a coil spring 11 interposed between-the head and a shoulder 12 between an enlarged and reduced portion of the central bore. Suitable sealing cement, indicated at 13, fills up the bore to seal'the same, and fixedly holds the insulator parts in assembled relation.

In the manufacture of the plug, the electrode is preferably assembled in the core prior to mounting of the core in the shell 2. This sub-assembly may consist of first inserting the spring 11 in the bore and then the electrode section 5 followed by the resistance element 6. Thereafter the threaded member 7 is inserted and threaded partly into the upper end of the core to clamp the resistance element between the adjacent faces of the sec tions 5 and 7 and initially compress the spring 11. In this position of the parts the tension of the spring serves to maintain the sections in tight contact one with the other. Cementitious material is then injected into the bore, which may be accomplished by placing the lower end of the electrode over the discharge nozzle of a cementing machine to force the cement under pressure into the open space of the-bore. Filling of the bore is complete when the operator observes seep- A w age of the cement around the screw-threads 95 at the upper end. After the bore is filled, the flow of cement is cut off and the terminal section 7 given a few more turns to thread it home and-move the abutment collar 9 into engagement with the top of the insulator; This additional adjustment of the section '7 further compresses the springll and compacts the cement to fill up any voids so as to eliminate air bubbles. After the cement hardens the electrode parts may be fixedly held in definite relation with each other and in tight electrical contact. Subsequently, the plug is completed by positioning and fixing the insu- The particular method of assembly is more fully described in my pending application Serial No. 418,572.

The plug thus provided, when d on an internal combustion engine, will ow the current to flow to and jump the gap at the lower end of the plug to fire explosive mixture in the usual fashion. The high resistance built into it will operate to damp out the train of waves that would ordinarily follow the passage of the spark and produce interference, and radio reception in the vicinity is thereby greatly improved.

As a modification of'the invention there is shown in Figure 2 a spark plug wherein 15 indicates an insulator core surrounding the central electrode, and having its screw-threaded hole and enlarged bore coated as at 16 with suitable resistive material. 'I'heterminal connector stud 1'7v is threaded into the coated hole into tight contact with the body 18 which in tum is held by the stud in tight contact with the head 19 of the central wire 20 extending through the core for co-operation at its lower end with the usual grounded electrode to provide the spark gap. The body 18 forms the resistance element to damp the objectionable oscillations and it may, if desired,

consist of such material as cement. In some cases it may be.found feasible to use the same substance for both the body l8 and the coating 18.

I claim: 1. In a spark plug, an insulator core having a shouldered bore, a terminal connector at the outer end of the bore, a headed pin projecting beyond the core at the inner end of the here to provide a sparking terminal, oscillation damping means bearing at opposite ends against the head of .the-pin and the connector respectively, fixing cement within the bore to secure the parts in place and'spring means between the head of the pin and'the shoulder of the bore to maintain the parts in bearing contact while the cement is setting. I

2. In a spark plug, an insulator having a bore therethrough, a connector section at the outer end of the bore, asparking terminal section at the inner end of the bore, an oscillation damping section interposed between the otherof said sections within the bore, and cementitious material securing said sections against displacement.

3. For use in an engine ignition system through which high frequency electrical oscillations occur intermittently and so tend to create disturbance to radio communication, a spark plug having integrally associated therewith a sectional electrode which includes a conductance element of an order to suppress the oscillations.

4. For use in an engine ignition system through which high frequency electrical oscillations occur intermittently and so tend to create disturbance to radio communication, a spark plug having an insulator core and a sectional electrode adapted to be cemented in the core and including a sparking section at the inner end of the core, a connector section at the outer end of the coreand an intermediate conductor section having conductance of an order to attenuate the disturbing oscillations.

5. In a spark plug, a sectipnalelectrode, an insulator core receiving the electrode, cementing material between the electrode and core, and spring means to maintain electrode sections in engagement with one another while the cement is setting.

HECTOR RABEZZANA. 

